Caption: Lilac leaf bud. Light micrograph of a cross-section of a bud from a lilac tree (Syringa vulgaris). The bud is comprised of an outer layer of six thick scale leaves (blue and purple), which have hairs to insulate the four inner small foliage leaves with lamina (dark purple), two inner triangular leaf stalks (petioles) and then a stem (pink) containing a ring of vascular bundles (dark pink). When the sap rises during the spring, the scale leaves fall off, the inner foliage leaves take up water and expand, and the central components grow outwards to form a new shoot. Magnification: x14 when printed 10 centimetres wide.